Generally, a heterogeneous network (Hetnet) is a network containing access nodes of differing power and/or coverage size. Access nodes may often be referred to as communications controllers, cells, base stations, NodeBs, evolved NodeBs, and the like. As an example, access nodes in a Hetnet may include a system of macro cells that operate at high power levels, a system of low power nodes, such as pico cells, radio heads, and relay nodes, which operate at reduced power levels. The macro cells and the low power nodes may be part of a planned network operated by one or more operators of the wireless communications system. Access nodes in a Hetnet may also include a system of ad-hoc nodes, such as femto cells, Home evolved NodeBs (HeNBs), and so on. The ad-hoc network may be user deployed access nodes that a user may add in order to improve performance in a small area, such as a home, an apartment building, a business, or so forth. Collectively, the access nodes (macro cells, low power cells, ad-hoc nodes, and the like) may be referred to as nodes without loss of generality.
A Hetnet may be considered to be a multi-layer communications system, with the macro cells making up a first layer, and the low power cells making up a second layer. A Hetnet with multiple relay nodes may offer the following benefits: lower power transmission (less power consumption and less electromagnetic pollution), enhanced coverage and capacity at low cost, and flexible deployments.